import * as vec2 from "../../src/vec2.js"

describe("vec2", function() {
    let out, vecA, vecB, result;

    beforeEach(function() { vecA = [1, 2]; vecB = [3, 4]; out = [0, 0]; });

    describe("create", function() {
        beforeEach(function() { result = vec2.create(); });
        it("should return a 2 element array initialized to 0s", function() { expect(result).toBeEqualish([0, 0]); });
    });

    describe("clone", function() {
        beforeEach(function() { result = vec2.clone(vecA); });
        it("should return a 2 element array initialized to the values in vecA", function() { expect(result).toBeEqualish(vecA); });
    });

    describe("fromValues", function() {
        beforeEach(function() { result = vec2.fromValues(1, 2); });
        it("should return a 2 element array initialized to the values passed", function() { expect(result).toBeEqualish([1, 2]); });
    });

    describe("copy", function() {
        beforeEach(function() { result = vec2.copy(out, vecA); });
        it("should place values into out", function() { expect(out).toBeEqualish([1, 2]); });
        it("should return out", function() { expect(result).toBe(out); });
    });

    describe("set", function() {
        beforeEach(function() { result = vec2.set(out, 1, 2); });
        it("should place values into out", function() { expect(out).toBeEqualish([1, 2]); });
        it("should return out", function() { expect(result).toBe(out); });
    });

    describe("add", function() {
        describe("with a separate output vector", function() {
            beforeEach(function() { result = vec2.add(out, vecA, vecB); });

            it("should place values into out", function() { expect(out).toBeEqualish([4, 6]); });
            it("should return out", function() { expect(result).toBe(out); });
            it("should not modify vecA", function() { expect(vecA).toBeEqualish([1, 2]); });
            it("should not modify vecB", function() { expect(vecB).toBeEqualish([3, 4]); });
        });

        describe("when vecA is the output vector", function() {
            beforeEach(function() { result = vec2.add(vecA, vecA, vecB); });

            it("should place values into vecA", function() { expect(vecA).toBeEqualish([4, 6]); });
            it("should return vecA", function() { expect(result).toBe(vecA); });
            it("should not modify vecB", function() { expect(vecB).toBeEqualish([3, 4]); });
        });

        describe("when vecB is the output vector", function() {
            beforeEach(function() { result = vec2.add(vecB, vecA, vecB); });

            it("should place values into vecB", function() { expect(vecB).toBeEqualish([4, 6]); });
            it("should return vecB", function() { expect(result).toBe(vecB); });
            it("should not modify vecA", function() { expect(vecA).toBeEqualish([1, 2]); });
        });
    });

    describe("subtract", function() {
        it("should have an alias called 'sub'", function() { expect(vec2.sub).toEqual(vec2.subtract); });

        describe("with a separate output vector", function() {
            beforeEach(function() { result = vec2.subtract(out, vecA, vecB); });

            it("should place values into out", function() { expect(out).toBeEqualish([-2, -2]); });
            it("should return out", function() { expect(result).toBe(out); });
            it("should not modify vecA", function() { expect(vecA).toBeEqualish([1, 2]); });
            it("should not modify vecB", function() { expect(vecB).toBeEqualish([3, 4]); });
        });

        describe("when vecA is the output vector", function() {
            beforeEach(function() { result = vec2.subtract(vecA, vecA, vecB); });

            it("should place values into vecA", function() { expect(vecA).toBeEqualish([-2, -2]); });
            it("should return vecA", function() { expect(result).toBe(vecA); });
            it("should not modify vecB", function() { expect(vecB).toBeEqualish([3, 4]); });
        });

        describe("when vecB is the output vector", function() {
            beforeEach(function() { result = vec2.subtract(vecB, vecA, vecB); });

            it("should place values into vecB", function() { expect(vecB).toBeEqualish([-2, -2]); });
            it("should return vecB", function() { expect(result).toBe(vecB); });
            it("should not modify vecA", function() { expect(vecA).toBeEqualish([1, 2]); });
        });
    });

    describe("multiply", function() {
        it("should have an alias called 'mul'", function() { expect(vec2.mul).toEqual(vec2.multiply); });

        describe("with a separate output vector", function() {
            beforeEach(function() { result = vec2.multiply(out, vecA, vecB); });

            it("should place values into out", function() { expect(out).toBeEqualish([3, 8]); });
            it("should return out", function() { expect(result).toBe(out); });
            it("should not modify vecA", function() { expect(vecA).toBeEqualish([1, 2]); });
            it("should not modify vecB", function() { expect(vecB).toBeEqualish([3, 4]); });
        });

        describe("when vecA is the output vector", function() {
            beforeEach(function() { result = vec2.multiply(vecA, vecA, vecB); });

            it("should place values into vecA", function() { expect(vecA).toBeEqualish([3, 8]); });
            it("should return vecA", function() { expect(result).toBe(vecA); });
            it("should not modify vecB", function() { expect(vecB).toBeEqualish([3, 4]); });
        });

        describe("when vecB is the output vector", function() {
            beforeEach(function() { result = vec2.multiply(vecB, vecA, vecB); });

            it("should place values into vecB", function() { expect(vecB).toBeEqualish([3, 8]); });
            it("should return vecB", function() { expect(result).toBe(vecB); });
            it("should not modify vecA", function() { expect(vecA).toBeEqualish([1, 2]); });
        });
    });

    describe("divide", function() {
        it("should have an alias called 'div'", function() { expect(vec2.div).toEqual(vec2.divide); });

        describe("with a separate output vector", function() {
            beforeEach(function() { result = vec2.divide(out, vecA, vecB); });

            it("should place values into out", function() { expect(out).toBeEqualish([0.3333333, 0.5]); });
            it("should return out", function() { expect(result).toBe(out); });
            it("should not modify vecA", function() { expect(vecA).toBeEqualish([1, 2]); });
            it("should not modify vecB", function() { expect(vecB).toBeEqualish([3, 4]); });
        });

        describe("when vecA is the output vector", function() {
            beforeEach(function() { result = vec2.divide(vecA, vecA, vecB); });

            it("should place values into vecA", function() { expect(vecA).toBeEqualish([0.3333333, 0.5]); });
            it("should return vecA", function() { expect(result).toBe(vecA); });
            it("should not modify vecB", function() { expect(vecB).toBeEqualish([3, 4]); });
        });

        describe("when vecB is the output vector", function() {
            beforeEach(function() { result = vec2.divide(vecB, vecA, vecB); });

            it("should place values into vecB", function() { expect(vecB).toBeEqualish([0.3333333, 0.5]); });
            it("should return vecB", function() { expect(result).toBe(vecB); });
            it("should not modify vecA", function() { expect(vecA).toBeEqualish([1, 2]); });
        });
    });

    describe("ceil", function() {
        beforeEach(function() { vecA = [Math.E, Math.PI]; });

        describe("with a separate output vector", function() {
            beforeEach(function() { result = vec2.ceil(out, vecA); });

            it("should place values into out", function() { expect(out).toBeEqualish([3, 4]); });
            it("should return out", function() { expect(result).toBe(out); });
            it("should not modify vecA", function() { expect(vecA).toBeEqualish([Math.E, Math.PI]); });
        });

        describe("when vecA is the output vector", function() {
            beforeEach(function() { result = vec2.ceil(vecA, vecA); });

            it("should place values into vecA", function() { expect(vecA).toBeEqualish([3, 4]); });
            it("should return vecA", function() { expect(result).toBe(vecA); });
        });
    });

    describe("floor", function() {
        beforeEach(function() { vecA = [Math.E, Math.PI]; });

        describe("with a separate output vector", function() {
            beforeEach(function() { result = vec2.floor(out, vecA); });

            it("should place values into out", function() { expect(out).toBeEqualish([2, 3]); });
            it("should return out", function() { expect(result).toBe(out); });
            it("should not modify vecA", function() { expect(vecA).toBeEqualish([Math.E, Math.PI]); });
        });

        describe("when vecA is the output vector", function() {
            beforeEach(function() { result = vec2.floor(vecA, vecA); });

            it("should place values into vecA", function() { expect(vecA).toBeEqualish([2, 3]); });
            it("should return vecA", function() { expect(result).toBe(vecA); });
        });
    });

    describe("min", function() {
        beforeEach(function() { vecA = [1, 4]; vecB = [3, 2]; });

        describe("with a separate output vector", function() {
            beforeEach(function() { result = vec2.min(out, vecA, vecB); });

            it("should place values into out", function() { expect(out).toBeEqualish([1, 2]); });
            it("should return out", function() { expect(result).toBe(out); });
            it("should not modify vecA", function() { expect(vecA).toBeEqualish([1, 4]); });
            it("should not modify vecB", function() { expect(vecB).toBeEqualish([3, 2]); });
        });

        describe("when vecA is the output vector", function() {
            beforeEach(function() { result = vec2.min(vecA, vecA, vecB); });

            it("should place values into vecA", function() { expect(vecA).toBeEqualish([1, 2]); });
            it("should return vecA", function() { expect(result).toBe(vecA); });
            it("should not modify vecB", function() { expect(vecB).toBeEqualish([3, 2]); });
        });

        describe("when vecB is the output vector", function() {
            beforeEach(function() { result = vec2.min(vecB, vecA, vecB); });

            it("should place values into vecB", function() { expect(vecB).toBeEqualish([1, 2]); });
            it("should return vecB", function() { expect(result).toBe(vecB); });
            it("should not modify vecA", function() { expect(vecA).toBeEqualish([1, 4]); });
        });
    });

    describe("max", function() {
        beforeEach(function() { vecA = [1, 4]; vecB = [3, 2]; });

        describe("with a separate output vector", function() {
            beforeEach(function() { result = vec2.max(out, vecA, vecB); });

            it("should place values into out", function() { expect(out).toBeEqualish([3, 4]); });
            it("should return out", function() { expect(result).toBe(out); });
            it("should not modify vecA", function() { expect(vecA).toBeEqualish([1, 4]); });
            it("should not modify vecB", function() { expect(vecB).toBeEqualish([3, 2]); });
        });

        describe("when vecA is the output vector", function() {
            beforeEach(function() { result = vec2.max(vecA, vecA, vecB); });

            it("should place values into vecA", function() { expect(vecA).toBeEqualish([3, 4]); });
            it("should return vecA", function() { expect(result).toBe(vecA); });
            it("should not modify vecB", function() { expect(vecB).toBeEqualish([3, 2]); });
        });

        describe("when vecB is the output vector", function() {
            beforeEach(function() { result = vec2.max(vecB, vecA, vecB); });

            it("should place values into vecB", function() { expect(vecB).toBeEqualish([3, 4]); });
            it("should return vecB", function() { expect(result).toBe(vecB); });
            it("should not modify vecA", function() { expect(vecA).toBeEqualish([1, 4]); });
        });
    });

    describe("round", function() {
        beforeEach(function() { vecA = [Math.E, Math.PI]; });

        describe("with a separate output vector", function() {
            beforeEach(function() { result = vec2.round(out, vecA); });

            it("should place values into out", function() { expect(out).toBeEqualish([3, 3]); });
            it("should return out", function() { expect(result).toBe(out); });
            it("should not modify vecA", function() { expect(vecA).toBeEqualish([Math.E, Math.PI]); });
        });

        describe("when vecA is the output vector", function() {
            beforeEach(function() { result = vec2.round(vecA, vecA); });

            it("should place values into vecA", function() { expect(vecA).toBeEqualish([3, 3]); });
            it("should return vecA", function() { expect(result).toBe(vecA); });
        });

        describe("symmetry", function() {
            it("should round negative values torwards negative infinity", function() { expect(vec2.round([], [-1.5, -1.5])).toBeEqualish([-2, -2]); });
        });
    });

    describe("scale", function() {
        describe("with a separate output vector", function() {
            beforeEach(function() { result = vec2.scale(out, vecA, 2); });

            it("should place values into out", function() { expect(out).toBeEqualish([2, 4]); });
            it("should return out", function() { expect(result).toBe(out); });
            it("should not modify vecA", function() { expect(vecA).toBeEqualish([1, 2]); });
        });

        describe("when vecA is the output vector", function() {
            beforeEach(function() { result = vec2.scale(vecA, vecA, 2); });

            it("should place values into vecA", function() { expect(vecA).toBeEqualish([2, 4]); });
            it("should return vecA", function() { expect(result).toBe(vecA); });
        });
    });

    describe("scaleAndAdd", function() {
        describe("with a separate output vector", function() {
            beforeEach(function() { result = vec2.scaleAndAdd(out, vecA, vecB, 0.5); });

            it("should place values into out", function() { expect(out).toBeEqualish([2.5, 4]); });
            it("should return out", function() { expect(result).toBe(out); });
            it("should not modify vecA", function() { expect(vecA).toBeEqualish([1, 2]); });
            it("should not modify vecB", function() { expect(vecB).toBeEqualish([3, 4]); });
        });

        describe("when vecA is the output vector", function() {
            beforeEach(function() { result = vec2.scaleAndAdd(vecA, vecA, vecB, 0.5); });

            it("should place values into vecA", function() { expect(vecA).toBeEqualish([2.5, 4]); });
            it("should return vecA", function() { expect(result).toBe(vecA); });
            it("should not modify vecB", function() { expect(vecB).toBeEqualish([3, 4]); });
        });

        describe("when vecB is the output vector", function() {
            beforeEach(function() { result = vec2.scaleAndAdd(vecB, vecA, vecB, 0.5); });

            it("should place values into vecB", function() { expect(vecB).toBeEqualish([2.5, 4]); });
            it("should return vecB", function() { expect(result).toBe(vecB); });
            it("should not modify vecA", function() { expect(vecA).toBeEqualish([1, 2]); });
        });
    });

    describe("distance", function() {
        it("should have an alias called 'dist'", function() { expect(vec2.dist).toEqual(vec2.distance); });

        beforeEach(function() { result = vec2.distance(vecA, vecB); });

        it("should return the distance", function() { expect(result).toBeEqualish(2.828427); });
    });

    describe("squaredDistance", function() {
        it("should have an alias called 'sqrDist'", function() { expect(vec2.sqrDist).toEqual(vec2.squaredDistance); });

        beforeEach(function() { result = vec2.squaredDistance(vecA, vecB); });

        it("should return the squared distance", function() { expect(result).toEqual(8); });
    });

    describe("length", function() {
        it("should have an alias called 'len'", function() { expect(vec2.len).toEqual(vec2.length); });

        beforeEach(function() { result = vec2.len(vecA); });

        it("should return the length", function() { expect(result).toBeEqualish(2.236067); });
    });

    describe("squaredLength", function() {
        it("should have an alias called 'sqrLen'", function() { expect(vec2.sqrLen).toEqual(vec2.squaredLength); });

        beforeEach(function() { result = vec2.squaredLength(vecA); });

        it("should return the squared length", function() { expect(result).toEqual(5); });
    });

    describe("negate", function() {
        describe("with a separate output vector", function() {
            beforeEach(function() { result = vec2.negate(out, vecA); });

            it("should place values into out", function() { expect(out).toBeEqualish([-1, -2]); });
            it("should return out", function() { expect(result).toBe(out); });
            it("should not modify vecA", function() { expect(vecA).toBeEqualish([1, 2]); });
        });

        describe("when vecA is the output vector", function() {
            beforeEach(function() { result = vec2.negate(vecA, vecA); });

            it("should place values into vecA", function() { expect(vecA).toBeEqualish([-1, -2]); });
            it("should return vecA", function() { expect(result).toBe(vecA); });
        });
    });

    describe("normalize", function() {
        beforeEach(function() { vecA = [5, 0]; });

        describe("with a separate output vector", function() {
            beforeEach(function() { result = vec2.normalize(out, vecA); });

            it("should place values into out", function() { expect(out).toBeEqualish([1, 0]); });
            it("should return out", function() { expect(result).toBe(out); });
            it("should not modify vecA", function() { expect(vecA).toBeEqualish([5, 0]); });
        });

        describe("when vecA is the output vector", function() {
            beforeEach(function() { result = vec2.normalize(vecA, vecA); });

            it("should place values into vecA", function() { expect(vecA).toBeEqualish([1, 0]); });
            it("should return vecA", function() { expect(result).toBe(vecA); });
        });
    });

    describe("dot", function() {
        beforeEach(function() { result = vec2.dot(vecA, vecB); });

        it("should return the dot product", function() { expect(result).toEqual(11); });
        it("should not modify vecA", function() { expect(vecA).toBeEqualish([1, 2]); });
        it("should not modify vecB", function() { expect(vecB).toBeEqualish([3, 4]); });
    });

    describe("cross", function() {
        let out3;

        beforeEach(function() {
            out3 = [0, 0, 0];
            result = vec2.cross(out3, vecA, vecB);
        });

        it("should place values into out", function() { expect(out3).toBeEqualish([0, 0, -2]); });
        it("should return out", function() { expect(result).toBe(out3); });
        it("should not modify vecA", function() { expect(vecA).toBeEqualish([1, 2]); });
        it("should not modify vecB", function() { expect(vecB).toBeEqualish([3, 4]); });
    });

    describe("lerp", function() {
        describe("with a separate output vector", function() {
            beforeEach(function() { result = vec2.lerp(out, vecA, vecB, 0.5); });

            it("should place values into out", function() { expect(out).toBeEqualish([2, 3]); });
            it("should return out", function() { expect(result).toBe(out); });
            it("should not modify vecA", function() { expect(vecA).toBeEqualish([1, 2]); });
            it("should not modify vecB", function() { expect(vecB).toBeEqualish([3, 4]); });
        });

        describe("when vecA is the output vector", function() {
            beforeEach(function() { result = vec2.lerp(vecA, vecA, vecB, 0.5); });

            it("should place values into vecA", function() { expect(vecA).toBeEqualish([2, 3]); });
            it("should return vecA", function() { expect(result).toBe(vecA); });
            it("should not modify vecB", function() { expect(vecB).toBeEqualish([3, 4]); });
        });

        describe("when vecB is the output vector", function() {
            beforeEach(function() { result = vec2.lerp(vecB, vecA, vecB, 0.5); });

            it("should place values into vecB", function() { expect(vecB).toBeEqualish([2, 3]); });
            it("should return vecB", function() { expect(result).toBe(vecB); });
            it("should not modify vecA", function() { expect(vecA).toBeEqualish([1, 2]); });
        });
    });

    describe("random", function() {
        describe("with no scale", function() {
            beforeEach(function() { result = vec2.random(out); });

            it("should result in a unit length vector", function() { expect(vec2.len(out)).toBeEqualish(1.0); });
            it("should return out", function() { expect(result).toBe(out); });
        });

        describe("with a scale", function() {
            beforeEach(function() { result = vec2.random(out, 5.0); });

            it("should result in a vector of correct length", function() { expect(vec2.len(out)).toBeEqualish(5.0); });
            it("should return out", function() { expect(result).toBe(out); });
        });

        describe("with a scale of zero", function() {
            beforeEach(function() { result = vec2.random(out, 0); });

            it("should result in a zero vector", function() { expect(vec2.len(out)).toBeEqualish(0); });
            it("should return out", function() { expect(result).toBe(out); });
        });
    });

    describe("transformMat2", function() {
        let matA;
        beforeEach(function() { matA = [1, 2, 3, 4]; });

        describe("with a separate output vector", function() {
            beforeEach(function() { result = vec2.transformMat2(out, vecA, matA); });

            it("should place values into out", function() { expect(out).toBeEqualish([7, 10]); });
            it("should return out", function() { expect(result).toBe(out); });
            it("should not modify vecA", function() { expect(vecA).toBeEqualish([1, 2]); });
            it("should not modify matA", function() { expect(matA).toBeEqualish([1, 2, 3, 4]); });
        });

        describe("when vecA is the output vector", function() {
            beforeEach(function() { result = vec2.transformMat2(vecA, vecA, matA); });

            it("should place values into vecA", function() { expect(vecA).toBeEqualish([7, 10]); });
            it("should return vecA", function() { expect(result).toBe(vecA); });
            it("should not modify matA", function() { expect(matA).toBeEqualish([1, 2, 3, 4]); });
        });
    });

    describe("transformMat2d", function() {
        let matA;
        beforeEach(function() { matA = [1, 2, 3, 4, 5, 6]; });

        describe("with a separate output vector", function() {
            beforeEach(function() { result = vec2.transformMat2d(out, vecA, matA); });

            it("should place values into out", function() { expect(out).toBeEqualish([12, 16]); });
            it("should return out", function() { expect(result).toBe(out); });
            it("should not modify vecA", function() { expect(vecA).toBeEqualish([1, 2]); });
            it("should not modify matA", function() { expect(matA).toBeEqualish([1, 2, 3, 4, 5, 6]); });
        });

        describe("when vecA is the output vector", function() {
            beforeEach(function() { result = vec2.transformMat2d(vecA, vecA, matA); });

            it("should place values into vecA", function() { expect(vecA).toBeEqualish([12, 16]); });
            it("should return vecA", function() { expect(result).toBe(vecA); });
            it("should not modify matA", function() { expect(matA).toBeEqualish([1, 2, 3, 4, 5, 6]); });
        });
    });

    describe("forEach", function() {
        let vecArray;

        beforeEach(function() {
            vecArray = [
                1, 2,
                3, 4,
                0, 0
            ];
        });

        describe("when performing operations that take no extra arguments", function() {
            beforeEach(function() { result = vec2.forEach(vecArray, 0, 0, 0, vec2.normalize); });

            it("should update all values", function() {
                expect(vecArray).toBeEqualish([
                    0.447214, 0.894427,
                    0.6, 0.8,
                    0, 0
                ]);
            });
            it("should return vecArray", function() { expect(result).toBe(vecArray); });
        });

        describe("when performing operations that takes one extra arguments", function() {
            beforeEach(function() { result = vec2.forEach(vecArray, 0, 0, 0, vec2.add, vecA); });

            it("should update all values", function() {
                expect(vecArray).toBeEqualish([
                    2, 4,
                    4, 6,
                    1, 2
                ]);
            });
            it("should return vecArray", function() { expect(result).toBe(vecArray); });
            it("should not modify vecA", function() { expect(vecA).toBeEqualish([1, 2]); });
        });

        describe("when specifying an offset", function() {
            beforeEach(function() { result = vec2.forEach(vecArray, 0, 2, 0, vec2.add, vecA); });

            it("should update all values except the first vector", function() {
                expect(vecArray).toBeEqualish([
                    1, 2,
                    4, 6,
                    1, 2
                ]);
            });
            it("should return vecArray", function() { expect(result).toBe(vecArray); });
            it("should not modify vecA", function() { expect(vecA).toBeEqualish([1, 2]); });
        });

        describe("when specifying a count", function() {
            beforeEach(function() { result = vec2.forEach(vecArray, 0, 0, 2, vec2.add, vecA); });

            it("should update all values except the last vector", function() {
                expect(vecArray).toBeEqualish([
                    2, 4,
                    4, 6,
                    0, 0
                ]);
            });
            it("should return vecArray", function() { expect(result).toBe(vecArray); });
            it("should not modify vecA", function() { expect(vecA).toBeEqualish([1, 2]); });
        });

        describe("when specifying a stride", function() {
            beforeEach(function() { result = vec2.forEach(vecArray, 4, 0, 0, vec2.add, vecA); });

            it("should update all values except the second vector", function() {
                expect(vecArray).toBeEqualish([
                    2, 4,
                    3, 4,
                    1, 2
                ]);
            });
            it("should return vecArray", function() { expect(result).toBe(vecArray); });
            it("should not modify vecA", function() { expect(vecA).toBeEqualish([1, 2]); });
        });

        describe("when calling a function that does not modify the out variable", function() {
            beforeEach(function() {
                result = vec2.forEach(vecArray, 0, 0, 0, function(out, vec) {});
            });

            it("values should remain unchanged", function() {
                expect(vecArray).toBeEqualish([
                    1, 2,
                    3, 4,
                    0, 0,
                ]);
            });
            it("should return vecArray", function() { expect(result).toBe(vecArray); });
        });
    });
    
    describe('rotate', function(){
		describe('rotation around world origin [0, 0, 0]', function(){
			  beforeEach(function(){ vecA = [0, 1]; vecB = [0, 0]; result = vec2.rotate(out, vecA, vecB, Math.PI); });
			  it("should return the rotated vector", function(){ expect(result).toBeEqualish([0, -1]); });
		});
		describe('rotation around an arbitrary origin', function(){
			  beforeEach(function(){ vecA = [6, -5]; vecB = [0, -5]; result = vec2.rotate(out, vecA, vecB, Math.PI); });
			  it("should return the rotated vector", function(){ expect(result).toBeEqualish([-6, -5]); });
		});
	});
    
    describe("angle", function() {
        it("should always return the positive angle between 0 and pi", function() {
            expect(vec2.angle([1, 0], [1, 2]))
                .toBeEqualish(1.10714);
            expect(vec2.angle([1, 2], [1, 0]))
                .toBeEqualish(1.10714);
            expect(vec2.angle([-1, 0], [1, 2]))
                .toBeEqualish(2.03445);
            expect(vec2.angle([1, 2], [-1, 0]))
                .toBeEqualish(2.03445);
        });
        it("should not modify the arguments", function() {
            let a = [1, 0], b = [1, 2];
            vec2.angle(a, b);
            expect(a).toBeEqualish([1, 0]);
            expect(b).toBeEqualish([1, 2]);
        });
    });

    describe("signedAngle", function() {
        it("should always return the signed angle between -pi and pi", function() {
            expect(vec2.signedAngle([1, 0], [1, 2]))
                .toBeEqualish(1.10714);
            expect(vec2.signedAngle([1, 2], [1, 0]))
                .toBeEqualish(-1.10714);
            expect(vec2.signedAngle([-1, 0], [1, 2]))
                .toBeEqualish(-2.03445);
            expect(vec2.signedAngle([1, 2], [-1, 0]))
                .toBeEqualish(2.03445);
        });
        it("should not modify the arguments", function() {
            let a = [1, 0], b = [1, 2];
            vec2.signedAngle(a, b);
            expect(a).toBeEqualish([1, 0]);
            expect(b).toBeEqualish([1, 2]);
        });
    });

    describe("str", function() {
        beforeEach(function() { result = vec2.str(vecA); });

        it("should return a string representation of the vector", function() { expect(result).toEqual("vec2(1, 2)"); });
    });

    describe("exactEquals", function() {
        let vecC, r0, r1;
        beforeEach(function() {
            vecA = [0, 1];
            vecB = [0, 1];
            vecC = [1, 2];
            r0 = vec2.exactEquals(vecA, vecB);
            r1 = vec2.exactEquals(vecA, vecC);
        });

        it("should return true for identical vectors", function() { expect(r0).toBe(true); });
        it("should return false for different vectors", function() { expect(r1).toBe(false); });
        it("should not modify vecA", function() { expect(vecA).toBeEqualish([0, 1]); });
        it("should not modify vecB", function() { expect(vecB).toBeEqualish([0, 1]); });
    });

    describe("equals", function() {
        let vecC, vecD, r0, r1, r2;
        beforeEach(function() {
            vecA = [0, 1];
            vecB = [0, 1];
            vecC = [1, 2];
            vecD = [1e-16, 1];
            r0 = vec2.equals(vecA, vecB);
            r1 = vec2.equals(vecA, vecC);
            r2 = vec2.equals(vecA, vecD);
        });
        it("should return true for identical vectors", function() { expect(r0).toBe(true); });
        it("should return false for different vectors", function() { expect(r1).toBe(false); });
        it("should return true for close but not identical vectors", function() { expect(r2).toBe(true); });
        it("should not modify vecA", function() { expect(vecA).toBeEqualish([0, 1]); });
        it("should not modify vecB", function() { expect(vecB).toBeEqualish([0, 1]); });
    });

    describe("zero", function() {
        beforeEach(function() {
            vecA = [1, 2];
            result = vec2.zero(vecA);
        });
        it("should result in a 2 element vector with zeros", function() { expect(result).toBeEqualish([0, 0]); });
    });
});
